Insulated shipping containers such as those used in over-the-road, rail, and ocean going containers often include panels (walls, roofs, and floors) formed from inner plates, outer plates, and foaming heat preservation layers between the plates. While the walls act as a substantial thermal and vapor barrier, the connections between the panels may provide gaps or cracks through which heat and vapor may pass.
In some instances a wall panel is connected to the roof panel via a piece of metal that is secured to both the upper portion of the wall panel and the side of the roof panel. Often, the metal sheet will be secured to the panels via blind rivets, however, since there are gaps at the rivets, and the rivet mandrel may not properly seal, it is easy for water vapor in the container body to invade into the heat preservation layer via the gaps at the rivets or the rivet mandrel. Any gaps between the panels reduce the effect of the heat preservation layer. In addition, in this traditional connecting manner, the connector is secured to the inner side panel and the inner roof sheet in a hard mechanical manner that does not compensate for flexure that may occur during transport of the container.
During loading or unloading of the cargo from the container, the metal piece securing the wall panel to the roof panel may deform based on the flexure of the roof panel, side panel, or floor panel. Over time, further flexure may act to diminish the sealing properties of the metal piece. In addition to issues associated with the gradual degradation of the sealing piece, the installation of metal pieces between the roof panel and the wall panel often requires specialized clamping tools as well as rivets.